by Dave Coleman
If you find yourself in Germany with a day to kill, you could do worse than Googling “rotary musem Germany.” I did just that, and stumbed into the Museum Autovision in Altussheim, about a one-hour autobahn blast south of Frankfurt. For a rotary nerd like me, this place is a mecca of obscure little triangles. It's a fascinating look at that forgotten decade when the rotary engine was the future. Too bad I couldn't read most of the signs…
The rotary hall is just one small room in a museum mostly intended for sowing the seeds of engineerdism in students. It's a dense room full of historcal gems, though.
The NSU RO80 was the first attempt at a real, mainstream rotary-powered car. It was a technologically impressive machine with lots of features that seemed like a good idea at the time, like front-wheel drive, inboard disk brakes and, well, a rotary engine… Visually, it could easily have been mistaken for a mid '80s Audi, even though it was built 20 years earlier. This is the cutaway auto-show special used at the car's debut at the Frankfurt motor show. The elaborate hydraulic system that opens the hood and drops the side is still functional.
Autovision's collection of rotary engines you've never seen before is surprising.
On the left is the first NSU rotary prototype. This is actually the first rotary engine ever where the rotor housing itself didn't rotate. Felix Wankel hated the idea, and right behind these engines is a blown up copy of the nastygram Wankel sent to NSU telling them they fucked up his brilliant engine design. Of course, his original design was so unreliable it made an NSU Spyder seem as reliable as a Volvo 240.
The engine on the right is the second prototype engine, in its 27th iteration. Each iteration had the spark plug location moved half a millimeter. #27 was the best location.
All rotary engines are built under a license agreement with NSU. Except the ones developed behind the iron curtain. This tiny 1-rotor engine is actually an East-German prototype developed for the Trabant. Because all East-German cars were 2-strokes anyway, gas stations only pumped pre-mix. With oil already mixed in the gas, this engine had no need for an oil injection system. Such are the engineering benefits of communisim.
This one-of-a-kind prototype 3-rotor was designed for a high-output version of the RO-80 that never saw production.
Much of the early excitement around rotaries was the ability to endlessly stack up rotors to make engines as big and powerful as necessary. These muti-piece eccentric shafts were an early attempt at making the engines modular. I'm guessing they're NSU, but I don't really know.
Mazda is big on hydrogen rotaries these days, but they're not the first to that party. This is an NSU-built hydrogen rotary prototype. You can just see the unique combustion pocket (in red, on the rotor face) designed to help mix the hydrogen and air before ignition.
Also, if you're a student of rotary evolution, you'll notice the coolant passages suggest this one is pretty well evolved. Early rotaries from both NSU and Mazda had self-contained water passages around each trochoid, with coolant entering the combustion side and flowing around the housing to exit on the intake side. The multiple o-ring-grooved holes around this housing suggest coolant flowed front to back through the engine like modern Mazdas. Also, notice there is no o-ring on the top right, which is the intake region, where no heat is generated, and thus no coolant is necessary. Mazda handles this by just restricting the coolant flow in this area.
The rear-engine, single-rotor NSU Spyder was the first production rotary-powered car. In this pristine example, you can see the radiator hoses entering and exiting the top of the rotor housing, indicating the early-style coolant flow.
The 81,000 km on this NSU Spyder's odometer suggest it's on its 4th engine…
If rotary engines sound like chainsaws, what does a rotary chainsaw sound like?
What about a rotary lawnmower?
Or what about a rotary-powered waterski machine? What's a waterski machine?
THIS is a waterski machine. For the waterski enthusiast without any friends…
|This thing is so awesome I don't even need to write a caption.|
|This Dutch motorcycle promised to be monstrously powerful, packing a 1,000cc 1-rotor engine (no telling how big it really was, as there was quite a bit of debate over how to define rotary displacement in the engine's early years). The engine was lifted from the small Citroen car (the silver one in the middle, below) and used a Porsche-designed gearbox. The bike, apparently, did not live up to its monstrous promise, and the company went bankrupt.|
If you get a chance to visit Museum Autovision yourself, be warned, they seem to be open only Thursday through Sunday. Do yourself a favor and bring someone who can read German. Or be lucky, like me, and get a long guided tour from museum owner Horst Schultz. To pull off the latter, I suggest wearing a Mazda jacket and travelling with with a handful of Mazda engineers. I'm guessing that improves your odds of a personal tour.